The present invention relates to an apparatus for selecting a centrifugal fluid machine having a required performance from among a plurality of centrifugal fluid machines. The present invention also relates to a computer-implemented method for selecting a centrifugal fluid machine, and a computer-readable storage medium having a program recorded thereon for selecting a centrifugal fluid machine.
Centrifugal fluid machines, e.g., pumps, have a performance range for which they are suited. This performance range can be described more specifically in terms of flow-head characteristics (Q-H characteristics). As shown in FIG. 4, a performance range suitable for a particular pump includes flow rates and heads located between a Q-H characteristic curve Y1 with an impeller having a diameter of 100 mm and a Q-H characteristic curve Y2 with an impeller having a diameter of 50 mm, or half the size, in the cases where parts other than an impeller housed in a pump casing are not changed, but the impeller is changed only in diameter. Left and right solid lines STA and END that are shown in FIG. 4 are a starting line and an ending line, respectively. Even if a pump satisfies the required performance (e.g., flow rate and head), the efficiency of the pump is decreased when the flow rate is too large or too small. Operation of a pump in an inefficient state increases the running cost and the like. Therefore, the starting line STA and the ending line END are provided in order not to include this operating region in the performance range of the pump.
When customers have requested a pump having a prescribed performance (for example, desired flow rate and head), the most effective pump (pump diameter and model number) having the required performance has heretofore been selected from numerous types of pumps in the following manner.
The performance ranges for respective pumps which are different from each other are prestored in a storage device of a computer in the form shown in FIG. 5. In this case, the performance ranges of the respective pumps overlap one another in some areas. In the overlapped areas, one pump is preferentially selected from among the pumps having the overlapped performance ranges. The performance ranges shown in FIG. 5 are numbered from {circle around (1)} through {circle around (7)} to indicate the priority of the corresponding pump. The performance ranges of pumps having a higher priority are displayed in front. In FIG. 5, the performance ranges are drawn with solid lines to indicate that they are in front of other performance ranges and with dotted lines to indicate that they are at the back of the ranges with the solid lines. The order of priority is artificially predetermined based on various conditions, for example, which diameters and models of pumps capable of providing the same performance are more cost effective.
When performance data (flow and head) requested by a customer is inputted into a computer, the computer detects which pump has a performance range that satisfies the required performance data, by comparing the inputted performance data to the data shown in FIG. 5, and then outputs the detected pump (diameter and model number).
However, the performance ranges of the respective pumps which are expressed by the data shown in FIG. 5 are complicated. The only performance ranges with simple configurations are those for pumps numbered {circle around (1)} and {circle around (2)} which have the highest priority. The performance ranges of all other pumps have more complicated forms because they are overlapped by the performance ranges of pumps having a higher priority. Therefore, complicated calculations and complicated data are required to determine whether or not the desired performance is included in these complicated areas, thereby increasing not only the complexity of the processing program, but also the time required to perform the selection process.
The present invention has been made in view of the above drawbacks. It is therefore an object of the present invention to provide an apparatus for easily selecting a centrifugal fluid machine having a required performance from among a plurality of centrifugal fluid machines having an order of priority. Another object of the present invention is to provide a computer-implemented method for selecting a centrifugal fluid machine, and a computer-readable storage medium having a program recorded thereon for selecting a centrifugal fluid machine.
In order to attain these objects, according to the present invention, there is provided an apparatus for selecting a centrifugal fluid machine having a required performance from among a plurality of centrifugal fluid machines. The apparatus comprises: an input device for inputting required performance data for a centrifugal fluid machine; a storage device for storing data regarding respective performance ranges of a plurality of centrifugal fluid machines and selection priorities for the respective centrifugal fluid machines; a selecting unit for selecting a centrifugal fluid machine by determining which of the performance ranges stored in the storage device for the plurality of centrifugal fluid machines satisfies the required performance data inputted by the input device, in order of higher selection priority stored in the storage device; and an output device for outputting data for the centrifugal fluid machine selected by the selecting unit.
Further, according to the present invention, there is provided a computer-implemented method for selecting a centrifugal fluid machine having a required performance from among a plurality of centrifugal fluid machines. The method comprises: prestoring data regarding respective performance ranges of a plurality of centrifugal fluid machines in a storage device with assigning selection priorities to the respective centrifugal fluid machines; inputting required performance data for a centrifugal fluid machine; and selecting a centrifugal fluid machine by determining which of the performance ranges stored in the storage device for the plurality of centrifugal fluid machines satisfies the inputted performance data, in order of higher selection priority stored in the storage device.
By selecting a centrifugal fluid machine in this manner, comparisons between the respective performance ranges and the required performance are simplified, so that calculations for these comparisons and the processing program are simplified. As a result, the time required to perform the selection process is shortened.
Here, the performance of the centrifugal fluid machine is the performance related to flow-head characteristics, flow-efficiency characteristics, flow-suction (NPSH) characteristics, or flow-power characteristics, for example. The performance range of the centrifugal fluid machine is the range of performance (related to flow-head characteristics, for example) suited to that particular centrifugal fluid machine.
This type of method for selecting a centrifugal fluid machine with a computer is implemented by a program for selecting a centrifugal fluid machine, which is stored on and provided by a storage medium.
Specifically, according to the present invention, there is provided a computer-readable storage medium having a program recorded thereon for executing a procedure with a computer. The procedure comprises: inputting required performance data for a centrifugal fluid machine; selecting a centrifugal fluid machine by determining which of performance ranges for a plurality of centrifugal fluid machines satisfies the inputted performance data with use of data regarding performance ranges of a plurality of centrifugal fluid machines prestored in a storage device and selection priorities for the respective centrifugal fluid machines prestored in the storage device, in order of higher selection priority stored in the storage device; and outputting data regarding the selected centrifugal fluid machine.